The airlines always issue a reminder to be in the airport at least 2 hours before the flight - that would take care of the check-in and other required procedures like the immigration. But here in Metro Manila, we usually leave the house early to be in the airport 4 hours before the flight. It is all right to wait instead of coming in late and be left by the plane. It would be a big disaster if that happens because we usually get accommodations online and had already paid it by the reserved days. There are so many cases of missing their flights in this Manila airport due to the extreme traffic sometimes. And there is no other route but the road with construction going on. So the advice to tourists is to be early to the airport.